forex-historical

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations provided, so description carries full burden. It discloses source (Frankfurter/ECB), free status, date range, weekend/holiday fallback, and max time-series range. Missing error handling or rate limits, but adequate for a free API.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Single paragraph, front-loaded with purpose, every sentence adds value. No redundant or vague statements.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Covers source, date range, weekend behavior, and siblings. No output schema, but description explains return structure ('rates keyed by date'). Lacks example output or error scenarios, but still complete enough for selection.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so baseline 3. Description adds overall context (single date vs range, default base USD, 30 currencies) but doesn't significantly enhance individual parameter meanings beyond schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description starts with 'Historical ECB exchange rates — single date lookup or time-series range', clearly stating the tool's function. It explicitly distinguishes from the sibling 'forex-rates' by noting it provides retrospective data.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description lists specific use cases (tax-date FX rates, historical expense reconciliation, multi-year trend analysis, point-in-time currency conversion) and mentions weekend/holiday behavior. It implies real-time needs should use 'forex-rates', but lacks explicit when-not-to-use guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.